This invention concerns equipment for handling powdered, granulated or other particulate solid materials and more especially equipment of the kind (hereinafter termed "of the kind referred to") used to assist the discharge of such materials from intermediate bulk containers adapted to be used repeatedly and popularly referred to within the industry as "multi-trip big bags".
Intermediate bulk containers in the form of large bags usually having an inner liner are becoming increasingly commonly used for the storage and dispensing of bulk particulate solids. Those adapted for repeated use have a tubular spout on their underside which must be untied and released to permit discharge.
The inner liner serves many purposes. The outer bag can be used many times without risk of contamination by inserting a replacement liner each time the bag is used. The inner liner prevents egress of very fine powders through the weave or seams of the outer bag. The liner prevents ingress of water to the product during transport of the bag and gives some measure of protection to the product if the outer bag should become damaged.
A major disadvantage of using an internal liner is the problem that occurs during the discharge of material from the bag. The common practice of discharging a bag is simply to hang the bag by four loops, open the spout on the outer bag, and unfasten the goose-neck of the internal liner, thus allowing the product to discharge freely or through a discharging machine. As the bag discharges the level of material eventually drops to a point where there is insufficient pressure to hold the liner against the walls of the bag, with the result that the liner slips and blocks the discharge outlet, or alternatively the liner drops through the spout and runs the risk of becoming entangled with the handling equipment below.
Various attempts to overcome this disadvantage by tying the upper end of the liner to support means before discharge have not proved wholly satisfactory since the liner can still collapse and interfere to some extent with discharge, as it sometimes can even when connected to cord means extendable against resilient means to draw the liner upwardly from the outer bag as emptying proceeds.